STUDIES OF THE PINK BOLLWORM IN MEXICO 41 
Table 31. — Temperature, in degrees Fahrenheit, on surface of, and in, soil between 
cotton rows in the field 
Date 
Hour 
Surface 
1 inch 
beneath 
surface 
2 inches 
beneath 
surface 
Maxi- 
mum air 
temper- 
ature 
1921 
Sept. 13 
12.30 p.m. 
2.30 p.m. 
4.30 p.m. 
10.00 a.m. 
12.30 p.m. 
2.30 p.m. 
4.30 p.m. 
10.30 a.m. 
12.30 p.m. 
2.30 p.m. 
°F 
142 
141 
123 
128 
146 
138 
114 
128 
141 
130 
124 
123 
116 
101 
115 
124 
112 
102 
114 
112 
o -p 
113 
112 
108 
92 
106 
111 
110 
94 
102 
102 
o F 
95 
Sept. 14... 
96 
Sept. 15 
92 
A temperature sufficient to kill the pink bollworm in a very short 
time is reached on the surface of the soil, and the soil, even as deep 
as 1 inch below the surface, becomes hot enough on some days to kill 
in time. All these readings were taken between the cotton rows, 
where the soil was exposed to the direct rays of the sun. 
Early in the morning of September 14, infested blooms were placed 
in and on the surface of the soil in direct sunlight and in the shade of 
cotton plants. These blooms had been collected from plants and 
allowed to dry several days in the laboratory. Ten blooms, each 
containing a living larva, were used in each experiment. Late in 
the afternoon the blooms were removed and examined. The results 
are given in Table 32. 
Table 32. 
■Effect of solar heat on pink bollworm larvae in blooms in and on the 
surface of soil in sunlight and in shade 
Location 
Sunlight 
'Shade 
On surface 
10 dead larvae . . . ... 
4 live larvae, 6 empty blooms. 
2 inches beneath surface. 
6 live larvae, 4 empty blooms 
5 live larvae, 5 empty blooms 
7 live larvae, 3 empty blooms. 
4 inches beneath surface ... . . . 
2 live larvae, 8 empty blooms. 
All larvae on the surface in the sun were killed. All larvae in the 
other locations either lived or left the blooms. The maximum air 
temperature on this day was 96° F. 
A similar experiment was conducted a few days later with pupae in 
blooms. After exposure the pupae were removed and placed in vials 
so that emergences of moths could be noted. The results are given 
in Table 33. 
Table 33. — Effect of solar heat on pupx in shed blooms in and on the surface of the 
soil in sunlight and, in shade 
Sunlight 
Shade 
Location 
Total 
pupae 
Moths 
emerged 
Total 
pupae 
Moths 
emerged 
On the surface ... ... 
14 
13 
12 

10 
11 
14 
9 
Test omitted. 
Test omitted. 
